Toxicity expertIntroduction:

Last month, a number of flight attendants filed suit against an airline manufacturer, alleging that toxic fumes from the plane’s exhaust air-conditioning system were released and caused each of the litigants to experience immediate and longer-term health problems. In the midst of this litigation, various toxicity experts have begun to weigh in on the issue of whether or not bleed exhaust systems, which are used by the vast majority of airline manufacturers, do, in fact, pose health risks to passengers and/or crew-members.


As one science reporter has explained, part of the problem regarding the issues being litigated is that “Despite decades of worry over these ‘fume events,’ scientists still don’t really know if they’re harmful.” Dan Vergano, “Here’s What We Actually Know About Toxic Fumes on Airplanes,” BuzzFeed News, Jun. 24, 2015. In fact, allegations about purportedly toxic fumes causing ailments among passengers and crew members have been made since the 1950s but, to date, there is still very little information to substantiate such claims. See id.

At the heart of the issue is the safety of the systems most planes use for air-conditioning, which are known as “bleed” exhaust systems. In a bleed exhaust system, so-called “bleed” air is simply compressed air that is produced by the turbine engines of a plane, taken from the aircraft’s turbine engines, and used for cabin climate control (such as air-conditioning). Airline manufacturers implement bleed air systems in order to pressurize the entire cabin instead of supplying air to each individual passenger. To date, nearly every commercial aircraft utilizes a bleed air or bleed exhaust system.

The plaintiffs, who allege that the exhaust system caused toxic fumes to bleed into the cabin and affect the quality of the air they took in, claim that such systems are at fault for their ailments. As one analyst explains: “The central health claim in the new case is…that leaks of synthetic oil vaporized in the jet’s engines, where temperatures can reach 900 degrees, releasing into the air organophosphates linked to neurological damage.” Id.

However, the toxicity experts have by no means reached a consensus on the issues being litigated. In fact, of the key questions being asked by medical and aviation experts is this: If, indeed, the exhaust system caused such toxicity to render the litigants unconscious and chronically ill, why were no passengers or pilots harmed?

“’Why are there no reports of ill health from the passengers who were breathing the same cabin air, nor from the pilots on that flight who were also breathing the same bleed air?’ aviation medicine expert Michael Bargshaw of King’s College London asked. Bargshaw concluded that a “worst case” fume incident in an airplane would only be one-quarter of the concentration needed to cause any ill effects — too low for any ‘medically feasible’ injuries.” Id.

Barghsaw’s question is one that many experts who represent airline manufacturers feel is an important one, and which disproves that the toxicity of fumes released in an aircraft’s bleed exhaust system was to blame.

However, toxicity experts on both sides of the debate are weighing in with valid points and counter-points, with the ultimate conclusion being that perhaps there simply is not enough data available at this time to reach a conclusion. The Indoor Air Journal “released a study finding that reports of engine fume events were very rare and spread across all passenger aircraft…from 2007 to 2012. That means that thousands of airplanes will need years of monitoring (with the kinds of cheap monitors that NASA is still developing) before we actually know the scope of cases like whatever happened [during the incident in question with the recent litigation].” Id.


Questions will continue to arise over the toxicity of bleed exhaust systems as the litigation evolves, and toxicity expert witnesses will play a crucial role in determining whether an aircraft manufacturer can be held legally responsible for alleged toxic exposure to certain fumes. The debate is heated, with many aviation experts insisting that commercial jets provide better air quality than cars or even classrooms. Meanwhile, the litigants and their attorneys have their own toxicity experts to attest to the alleged toxic effects experienced from bleed air systems. As this is the first litigation of its kind, it will bear watching for attorneys in the aviation field in the years to come toxic.


By: Kat S. Hatziavramidis, Attorney-at-Law